The present invention generally relates to a method and system for enhancing performance of a computer system, and more particularly, a method and system for enhancing efficiency of processing in a computer system and in a processor with multiple processing threads for use in a massively parallel supercomputer.
Traditional operating systems rely on a MMU (memory management unit) to create mappings for applications. However, it is often desirable to create a hole between application heap and application stacks. The hole catches applications that may be using too much stack space, or buffer overruns. If these conditions silently occur, debugging applications can be extremely difficult. Debugger applications may be used to perform a memory access check. The sizes of the stack and heap are dynamic as the application executes, and therefore, traditional operating systems do not fill the hole when a page-fault occurs in the hole. This causes a segmentation violation and, typically, termination of the program. However, traditional operating systems pay a penalty for this flexibility and must perform page faults as part of their normal execution. For high performance computing operating systems, such as supercomputers, for example, IBM® Blue Gene®, the operating system creates a static memory mapping at application startup. Thus, a disadvantage of current supercomputer systems is that the operating system's creation of a static memory mapping at application startup prevents usage of the traditional technique of using a hole in the MMU as described above.
It would therefore be desirable to provide a system and a method for an operating system to create mappings for applications when the operating system cannot create a hole between application heap and application stacks. Further, it would be desirable to provide a system and method for an operating system to create mappings as above when the operating system creates a static memory mapping at application startup, such as in a supercomputer. It would also be desirable to provide a system and method for an alternative to using a processor or debugger application or facility to perform a memory access check.